Because her father has to return to India for the sake of his mother, Komal must spend the summer with her uncle in Sun Hills. Her uncle is working there on a hi-tech workers visa. There aren't many kids and she spends a lot of her time alone. It is during one such time that she falls into the other dimension.
Komal thinks that she cannot go back until she has solved the problems of each world. At some point, late in the story, she finds that she can; but she chooses not to, because she's grown to care so much about the people of this place.
At one point, the head villain of a world will offer her the way home as a trick to try to get rid of her!
The main talismans will be keys. The keys will open the dimension doors to the next world.
Tufkin will join up with her right at the start, for companionship, comedy relief and to do other, practical things.